2, 4-diamino-7, 8-disubstituted pteridines



Patented Jan. 5, 1954 UNITED STATES PATENT OFFICE2,4-DIAMIN--7,8-DISUBSTITUTED PTERIDINES Norman Robert Campbell,Hertford, Maurice Edward Hugh Fitzgerald,

Henry Oswald J ackso Shirley, Croydon, and

n Collier, Hoddesdon,

England, assignors to Allen & Hanburys Limited, London, England, aBritish company No Drawing. Application October 17, 1950, Serial No.190,656

Claims priority, application Great Britain December 22, 1948 8 Claims.(Cl. 260-2515) NHz where R is a radical selected from the groupconsisting of alkyl radicals containing from two to eight carbon atoms,the benzyl radical, the anisyl radical and the cyclohexylmethyl radicaland R is a radical selected from the group consisting of alkyl radicalscontaining from two to eight carbon atoms, the benzyl radical, theanisyl radical and the cyclohexylmethyl radical.

In accordance with the present invention the novel pteridines may bemanufactured by condensing 2,4,5,6-tetraminopyrimidine or an acid saltthereof preferably the bisulphite with an adiketone on the generalformula I R in, where R is a radical selected from the group consistingof alkyl radicals containing from two to eight carbon atoms, the benzylradical, the anisyl radical and the cyclohexylmethyl radical and R is aradical selected from the group consisting of alkyl radicals containingfrom two to eight carbon atoms, the benzyl radical, the anisyl radicaland the cyclohexylmethyl radical.

The reaction may be carried out in an acid or an alkaline medium or inthe presence of an organic base such as piperidine and it is preferredto carry out the process in the presence of an alkali metal carbonateparticularly sodium or potassium bicarbonate.

Example 1 One gm.-mol. of dipropionyl was mixed with one gm.-mol. of2,4,5,6-tetraminopyrimidine acetate and 2.5 litres of acetic acid andthe whole boiled for 2 hours under reflux. The mixture was cooled andpoured into 20 litres of water, the pH adjusted to approximately 6.0 andthe solid product collected by filtration. The product was purified byrecrystallisation from ethanol and treatment with decolorising charcoal.The purified product was 6,7-diethyl-2,4-diaminopteridine of meltingpoint 280 C. and was a pale yellow solid.

Example 2 One gm.-mol. of di-isobutyryl was mixed with one gm.-mol. of2,4,5,6-tetraminopyrimidine acetate and 2.5 litres of 60% acetic acidand the whole boiled for 2 hours under reflux. The mixture was cooledand poured into 20 litres of water, the pH adjusted to approximately 6.0and the solid product collected by filtration. The product was purifiedby recrystallisation from ethanol and treatment with decolorisingcharcoal. The purified product was 6,7 -di-isopropyl-ZA-diaminopteridineof melting point 246 C. and was a pale yellow solid.

Example 3 One gm.-mol. of ethyl-4-methoxyphenyl diketone was mixed withone gm.-mo1. of 2,4,15,6- tetraminopyrimidine acetate and 2.5 litres of60% acetic acid, and the whole boiled for 2 hours under reflux. Themixture was cooled and poured into 20 litres of water, the pH adjustedto approximately 6.() and the solid product collected by filtration. Theproduct was purified by recrystallisation from ethanol and treatmentwith decolorising charcoal. The purified product was 6 anisyl 7 ethyl(or 7-anisyl-6-ethyl) -2,4-diaminopteridine of melting point 228 C. andwas a pale yellow solid.

Ethyl--methoxyphenyl diketone is prepared as follows: The methodemployed is based on that given in Organic Syntheses Coll, vol. 2, forthe preparation of isonitroso-propiophenone and also on the method ofPechmann and Muller (Ber.

' 'boiIe d for, 2 hours under reflux.

3 21, 2119; 22, 2128) for the preparation of methylphenyl diketone.

To a solution of l-methoxybutyrophenone (40.5 gms.) in ether (200 ml.)amyl nitrite (28.5 ml.) was added at a rate sufficient to keep the etherrefluxing. The reaction mixture was stirred vigorously and a rapidstream of hydrogen chloride gas was passed into it. After the additionof the amyl nitrite, the mixture was cooled; washed with a little waterand extracted with 10% sodium hydroxide solution. The alkaline extractwas freed from ether under reduced pressure on the water-bath, cooledand poured into a slight excess of concentrated hydrochloric acid mixedwith ice.

The crude a-isonitroso 4-methoxy-nrbutyrophenone was converted to thediketone by suspending it in 5% sulphuric acid (600 ml.) and steamdistilling. The distillate was extracted with benzene and the extractwashed with sodium carbonate solution, dried and distilled.

The diketone weighed 9 gms. and was a yellow liquid, boiling point 155(3/11 mm.

Example 4 One gm.-mol. of isopropyl-4-methoxyphenyl diketone was mixedwith one gm.-mol. of 2,45,6- tetraminopyrimidine acetate and 2.5 litresof 60% acetic acid and the whole boiled for 2 hours under refiux. Themixture was cooled and poured into 20 litres of water, the pH adjustedto approximately 6.0 and the solid product collected byfiltration. Theproduct was purified by recrystallization from ethanol and treatmentwith decolorising charcoal. The purified product was fianisyl'l-isopropyl (or 'l-anisyl-G-isopropyb- 2,4-diaminopteridine of meltingpoint 200 C. and wasa pale yellow solid.

The method of preparing isopropylA-methoxyphenyl diketone is based onthe method used for the preparation of ethyli-methoxyphenyl diketone.

4-methoxyisoyalerophenone (307.5 v gins.) was dissolvedin etherv (1.5litres). Into this solution was passed, a rapid stream of hydrogenchloride as and at the, same time a stream of methyl nitrite gasgenerated from sodium nitrite (132 gms. methyl alcohol (85 ml.) andwater, ('78 ml.) by the gradual addition of dilute sulphuric acidv(112-210 ml.). The sulphuric acid was added I at such a rate that themethyl nitrite produced kept the ether in the flask refluxing gently;the mixture was stirred rapidly.

When the addition was complete, the mixture was cooled and extractedwith 10% sodium hydroxide solution after first washing with a littlewater. The sodium hydroxide extract was freed fromether under reducedpressure on the waterbath, cooled and poured into excess concentratedhydrochloric acid and ice.

Thev crude isonitroso 4 methoxyisovalerophen'one was hydrolysed bysuspending it in 25% sulphuric acid (2 litres) and steam distilling toobtain the diketone. The distillate was extracted with benzene and theextract washed with sodium carbonate solution, dried and distilled.

The'yield of diketone was 54.7 gms in the form of ayellow liquid,boiling point 115 C./0.1 mm.

Example 5 One gm.-mol. of anisil was mixed with one gm.mol. of2,4,5,6-tetraminopyrimidine acetate and 2.5 litres of 60% acetic acidand the whole v H g The mixture was'cooled and poured into litres ofwater,

the pH adjusted to approximately 6.0 and the solid product collected byfiltration. The crude product was purified by extraction with hot waterand with benzene and finally recrystallisation from aqueous pyridine.The purified product was 6,7-diamsyl 2,4 diaminopteridine of meltingpoint 288 C. and was a yellow solid.

While in the above examples the condensation has been effected in anacid medium using 2,4,5,6- tetraminopyrimidin acetate in an acetic acidsolution, the process is also operative using other salts such as the2,4,5,fi-tetraminopyrimidine bisulphite in an acid or alkaline medium,or 2,45,6- tetraminopyrimidine in an alkaline medium.

This is illustrated in the following example:

Example 6.Preparation of 6,7-di-isopropyl-2,4- diaminopteridine Amixture of tetra-aminopyrimidine bisulphite (3.3 gins), 2,5-dimethylhexan-BA-dione (Ponzio, Gaaz. 30, II, 26) (1.0 gins), water (50 cos.)sodium. hydrogen carbonate (1.3 gms.) and ethanol (20 ccs.) was heatedto boiling under a reflux condenser for one hour. The mixture wascooled, diluted with an equal quantit of water and the crude productcollected by filtration. Thecrude material was purified byrecrystallisation from alcohol. The purified product was obtained in 90%of the theoretical yield, as a crystallinesolid melting at 246 C.

For purposes of comparison the following new compounds were also made bythe method described in Example 1:

6,7,-di-n-propyl-2,4-diaminopteridine of melting point 200 C.6,7-di-sec.-butyl-2,4-diaminopteridine of melting point 210 C.G-phenyl-l-ethyl (or 7-phenyl-6-ethyl)-2,4rdiaminopteridine of meltingpoint 280 C. 6-phenyl-7-isopropyl (orv 7-pheny1-6-isoprop D-ZA-diaminopteridine of melting point 242 C.

M jnimum inhibitory concentration 24 hours Itcr Jinc (2, i-diarnino)Dimethyl" 600 rig/ml. Dipllenyl. 300 g/ml. DiethyL. 20 p -lmlDi-n-propyl rig/m Di-isoprooyl l0 g lml. Di-soa-butyl 80 g/ml. 25-g./ml.

Wag/ml. ncnyl ethyl partial at 80 g/ml. Phcnylisopropyl 80 g/ml.

Fromthese results it will be seen that the compounds 6,? diisopropyl-2,4- diaminopteridine, 6,7 di ethyl 2,4 diaminopteridine and6,7-dianisyl-2,4-diaminopteridine are distinctly superior against Vibriochloreae to the other compounds prepared and very'much superior to theknown compounds, which result could: not be forecast from previousknowledge or a consideration of the structure of the compounds- Some ofthe compounds of the present invention are antagonists ofpteroylglutamic acid and thus are, useful against organisms requiring'pteroylglutamic acid. t

The following compounds are useful in respect of this aspect Of theinvention.

The following examples illustrate the preparation of these compounds.

Example 7.-Preparation of 6,7-di-n-butyZ-2,4- diamz'nopteridine Amixture of tetra-aminopyrimidine bisulphite (2.2 gms), decane-5,6-dione(Bloch, Lehr and Erlenmeyer, Helv. Chim. Acta, 1945, 28, 1406) (1.7gms.), 60% aqueous acetic acid (50 cos.) and ethanol (5 cos.) was heatedto boiling under a reflux condenser for three hours. The mixture wasthen poured into water (200 s.), the pH adjusted to approximately 7 bythe addition of a solution of sodium hydroxide and the precipitatedcrude product collected by filtration. The crude material wasrecrystallised from aqueous alcohol. The purified product6,7-di-n-butyl- 2,4-diaminopteridine, was obtained in 40% of thetheoretical yield as a pale yellow crystalline solid melting at 180 C.

Example 8.Preparation of 6,7-di-n-amyl-2,4-

diaminopteridine a solution of sodium hydroxide and the precipitatedcrude product collected by filtration. The crude material wasrecrystallised from aqueous alcohol. The purified product,6,7-di-namyl-2,4-diaminopteridine was obtained in 15% of the theoreticalyield as a pale yellow crystal-= line solid melting at 160 C.

Example .9.--Preparation of 6,7-di-isobutyl-2,4-

diammopterz'dine A mixture of tetra-aminopyrimidine bisulphite (2.2gms.), 2,7-dimethyl octan-4,5-dione (Ponzio, Gazz. 31, 1, 463, J. prakt,[2] 63, 368) (1.7 gms), 60% aqueous acetic acid (50 cos.) and ethanol (5cos.) was heated to boiling under a reflux condenser for three hours.The mixture was then poured into water (200 00s.), the pH adjusted toapproximately 7 by the addition of a solution of sodium hydroxide andthe precipitated crude product collected by filtration. The crudematerial was purified by chromatography in a mixture of chloroform andalcohol on a column of aluminium oxide and then recrystallised fromaqueous alcohol. The purified product,6,7-di-isobutyl-2,4-diaminopteridine was obtained in 30% of thetheoretical yield as a pale yellow solid, melting at 218 0.

Example 10.--Preparation of 6,7-din-propyl- 2,4-diaminopteridine Amixture of tetra-aminopyrimidine bisulphite (2.2 gms.), octan-4,5-dione(Bouveault, Bull. soc. chim., [3] 35, 652) (1.42 ems), 60%

aqueous acetic acid (50 cos.) and ethanol (5 cos.) was heated to boilingunder a reflux condenser for three hours. The mixture was then pouredinto Water (200 cos), the pH adjusted to approximately 7 by the additionof a solution of sodium hydroxide and the precipitated crude productcollected by filtration. The crude material was recrystallised fromalcohol. The purified product, 6,7 -di-npropyl -2,4- diaminopteridinewas obtained in 42% of the theoretical yield as a yellow crystallinesolid melting at 202 C.

Example 11.Preparation of 6,7-dibeneyl-2,4- diaminopteridz'ne A mixtureof tetra-aminopyrimidine bisulphite (2.2 gms), 1,4-diphenylbutan-2,3-dione (Ruggli and Zeller, Helv. Chem. Acta, 1945, 28, 741-6)(1.4 ems), 60% aqueous acetic acid (50 cos.) and ethanol (5 cos.) washeated to boiling under a reflux condenser for three hours. The mixturewas then poured into water (200 cos), the pH adjusted to approximately 7by the addition of a solution of sodium hydroxide and the precipitatedcrude product collected by filtration. The crude material wasrecrystallised from alcohol. The purified product,6,7-dibenzyl-2,4-diaminopteridine, was obtained in 20% of thetheoretical yield as a yellow crystalline solid melting at 258 C. withdecomposition.

Example 12.-Preparation of 6,7-oli-sec.butyl- 2,4-diamznopteridine at95-100 C. This hydroxyketone was oxidised to 3,6-dimethyloctan-4,5-dionein the following, manner: 4-hydr0Xy-3,6-dimethyloctan-5-one (1'7 gms.)was mixed with cupric acetate (40 gms.), acetic acid (100 cos.) andwater cos). The mixture was heated to boiling under a reflux condenser,with mechanical stirring, for two hours, then poured into Water (500ccs.). The mixture was extracted with benzene, the benzene extractwashed by shaking with a solution of sodium carbonate and freed fromwater by prolonged standing over solid potassium carbonate. Removal ofthe benzene, by distillation, left a crude oily product, which waspurified by distillation at reduced pressure. The purified product wasobtained as a yellow oil, boiling at 67-70 C. at a pressure of 12 mm.The yield of product was 10 gms.

A mixture of tetra-aminopyrimidine (3.3 gms.),3,6-dimethyloctan-4,5-olione, prepared as above (1.7 gms.), sodiumhydrogen carbonate (1.3 gms.), water (50 cos.) and ethanol (20 cos.) washeated to boiling under a reflux condenser for one hour. The mixture wascooled, diluted with an equal volume of water and the crude productcollected by filtration. The crude material was purified byrecrystallisation from aqueous alcohol. The purified product,6,7-di-sec.- butyl-2,4-diaminopteridine, was obtained in 53% of thetheoretical yield, as a yellow crystalline solid melting at 210 C.

Example 13.Preparation of 6,7-di-sec.-amyl- 2,4-diaminopteridz'ne5-hydroxy-4,7-dimethyldecan-6-one was prepared from 'ethyl-sec-caproatein 75% yield by the general method described by Snell and Mc-Elv'ain'wrg. Synth., 1943;.(3011. vol. II, 114). It

sium carbonate. Removal hydrochloride from decinormal "was db'mirid as anarly 'c'olourle's's oil boiling at 110-115" water. To this summer;was*sIoWIyadded'asGlU- tion of chromium meme '(1 "gm'si) in 50% aqueousacetic acid 1(14 cos.) Tli'e'iiiixturew'as poured into water (500 ccs.)'and extracted with benzene. The benzene "extract was washed with asolution of sodium carbonate and freed from water by prolonged standingover solid potasof benzene, by distillation, left a crude, oily,product, which was purified by distillation at "reduced pressure. The

' oil, boiling at 95-100" C. at a pressure "was heated to boiling underareflux condenser for three hours. The niixture'was cooled, di-

lut'ed with an equal volume oiwater and the crude product collectedbyffiltration, The crude material was purified by recrystallisation oithe hydrochloric acid, the base being regenerated by hydrochloride witha'hotsolution of sodium hydrogen carbonate and recrystallised fromalcohol. The purified product was obtained in l4% of the theoreticalyield, as a crystalline solid "melting at 172 C. Example14.--Pr'ep'aration of 6,7-di-cycloheazylmethyl-zA dicminopteridmeZ-hydro'xy 1,4 dicyclohexylbutan 3-one was prepared fromethylfey'lohexxtlacetate in 68% yield by the general method described bySnell and McElvain gore. 'Syntn, 194.3, Colhvol II, 114) It wasobtained'as 'anearly fcolourless liqjuid', b'oiling a 170430 c.atapressure or 0.3 m This hydroxylietor'ie was oxidised to l-A di'cyclohexylbutanlfl-fd ione in the following manp z-h dro gy': 1,4;-dicycloh'ex'ylbuta nf3fone, prepared as above (20 gins.) Wasdissolved inacetic acid (50 cos.) to this solution was added, "slowly, a,solution'of chromium trio'Xi-de (S'g'rns) in a 'iiiiiture or water (8has.) [and acetic'acid ('20 ccs.). The mixture was then pouredinto water(500 ms.) and extracted with benzene. The benzene extract was washedwith a solution of sodium carbonate and freed from water by prolongedstanding over solid potassium carbonate. Removal of benzene, bydistillation, left a crude oily product, which was purified bydistillation at reduced pressure. The purified product (12 gms.) wasobtained as a yellow oil, boil ing at 100 C. at a pressure of 0.05 mm,later solidifying to asolid melting at 52C.

.A mixture of tetra-aminopyrimidirie bis'ulphite (2.6 gm's.)1,4-di-cycloheXylbutan-23- dione (prepared as above) (1 .95 gins),sodium hydrogen carbonate (1 gm), water (40 cos.) and alcohol (16 ccs.)was heated to'b oiling' under a reflux condenser for one-hour. Themixture was cooled, diluted with an equalvoluine of water and the crudeproduct "collected by filtration. The crude materialwas purified byrecrystallisation irom alcohol. .The purified product was obtained in22% of the theoretical yield, as a crystalline solid melting at 230 C. p

The compoundsreferr'ed' to above were tested treatment of the 1 fortheir activity as antagonists of pteroylglutamic acid as compared withAminopterin (4-amino-pteroylglutamic acid) which is a powerlul FolicAcid antagonist for the organism Streptococcus jdcalis. In the followingtable the comparative activities are given as compared with4-aminoptero'ylglutamic acid taken as unity. Substance: V i v Activity4=amino-pteroylglutamic acid 1 6,7-dibenzyl 2,4-diaminopteridine 6,7-din-propyl-2,4-diaminopteridine 6,7-di-isopropyl-2,4-diaminopteridine6,7-di-n-butyl-2, l-diaminopteridine 6,'7di-isobutyl-2,4-diaminopteridine 6,7 di-sec-butyl-2,45diaminopteridine6,7-di n amyl-2A-diaminopteridine 6,7-di sec amyl z-diaminopteridine 6,7di cyclohexylmthyl 2,4 diaminopteridine I .M as moou wwc mow What weclaim is: I

l. Pteridines of the general formula where R is a radical selected fromthe group consisting of alkyl radicals containing from two to eightcarbon atoms, the benzy radical, the

anisyl radical and the cyclohexylmethyl radical and Elisa radicalselected vfrom the group concompound, 6,7-di-nwhere R is aradicals'elected from the group cons sting of alkyl radicals containingrrom two to elght carbon atoms, the benzyl radical, the

janisyl radical and the cycloh'e'xylmethyl radical lt' 1s a radicalselected from the group consisting of alkyl radicals containing from twoto eight carbonatoms, the benzyl radical, the anisyl radical and thecycloh'ekylmethyl radical, which comprises condensing a compoundselected from the groupconsisting of 2,4,5,fi-tetraminopyrimidine andits acid salts with an a-diketone' of the general formula RCI)=O whereR, is a radical selected from the group consisting of alkyl radicalscontaining from two to eight carbon atoms, the benzyl radical, theanisyl radical and the cyclohexylmethyl radical and R is a radicalselectedfrom the group consisting of alkyl radicals containing from two.to

N R NH:

N I N where R is a radical selected from the group consisting of alkylradicals containing from two to eight carbon atoms, the benzyl radical,the anisyl radical and the cyclohexylmethyl radical and R. is a radicalselected from the group consisting of alkyl radicals containing from twoto eight carbon atoms, the benzyl radical, the anisyl radical and thecyclohexylmethyl radical, which comprises condensing2,4,5,6-tetramlnopyrimidine bisulphite with an a-diketone of the 20general formula R =0 R'C=0 where R is a radical selected from the groupconsisting of alkyl radicals containing from two to eight carbon atoms,the benzyl radical, the anisyl radical and the cyclohexylmethyl radicaland R. is a radical selected from the group consisting of alkyl radicalscontaining from two to eight carbon atoms, the benzyl radical and theanisyl radical in the presence of an alkali metal carbonate and thecyclohexylmethyl radical.

NORMAN ROBERT CAMPBELL. MAURICE EDWARD HUGH FITZGERALD. HENRY OSWALDJACKSON COLLIER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,581,889 Timmis Jan. 8, 1952 OTHER REFERENCES Mallette etal., J. Am. Chem. 800., 69, 1814- 1816 (1947).

1. PTERIDINES OF THE GENERAL FORMULA
 7. A PROCESS FOR THE MANUFACTURE OFPTERIDINES OF THE GENERAL FORMULA